Schiff bases have been extensively studied for their biological and
pharmacological activities [1], as well as suitability for analytical
applications. The Schiff bases derived from o-vanillin and 1,2-
diaminobenzene (6-(((2-aminophenyl)imino)methyl)-2-methoxyphenol =L)
presents various protonation equilibria. Their application require a detailed
study of their solution chemistry. The spectroscopic and spectrofluorimetric
behavior in a wide pH range in the NaCl solutions are presented. The
compound exhibits a low solubility in aqueous solution and is unstable after
about a week. To study the acid base properties of this system have been
performed spectrophotometric and potentiometric measurements in
solutions containing low concentrations of buffer systems that do not affect
the acidbase behavior of the ligand. The measurements were carried out at
25 C in NaCl as ionic medium (0.1 1 M). The changes in the spectrum of
solutions of the ligand in dependence of the pH were used to determine the
constants of protolysis of the compound

Schiff bases have been extensively studied for their biological and
pharmacological activities [1], as well as suitability for analytical
applications. The Schiff bases derived from o-vanillin and 1,2-
diaminobenzene (6-(((2-aminophenyl)imino)methyl)-2-methoxyphenol =L)
presents various protonation equilibria. Their application require a detailed
study of their solution chemistry. The spectroscopic and spectrofluorimetric
behavior in a wide pH range in the NaCl solutions are presented. The
compound exhibits a low solubility in aqueous solution and is unstable after
about a week. To study the acid base properties of this system have been
performed spectrophotometric and potentiometric measurements in
solutions containing low concentrations of buffer systems that do not affect
the acidbase behavior of the ligand. The measurements were carried out at
25 C in NaCl as ionic medium (0.1 1 M). The changes in the spectrum of
solutions of the ligand in dependence of the pH were used to determine the
constants of protolysis of the compound